1. Field of the Invention
This invention relates to a device for controlling weft inserting in an air jet loom and a water jet loom or the like, and more particularly to a control device for weft inserting in a jet loom provided with an actuator for controlling the weft inserting.
2. Description of the Prior Art
In a jet loom, it is desired to control weft inserting so that a weft running condition, in particular, an arrival timing such as the angle of rotation (arrival angle) of a main shaft when a weft arrives at a predetermined position may become constant, in other words, so that the weft may be inserted in a predetermined running condition.
For this reason, in the jet loom, there has been proposed a technique which corrects at least one parameter selected from the pressure (designated as a "main pressure" in the present invention) of a fluid ejected from a main nozzle and the pressure (designated as a "subpressure" in the present invention) of a fluid ejected from a subnozzle or the like and controls an actuator thereof in order to correct at least one running data selected from the average value of arrival timing and the dispersion of arrival timing or the like.
However, in the jet loom, there are the cases where a direction for controlling one parameter so as to correct one running data to a predetermined value agrees or does not agree with a direction for controlling the above-mentioned one parameter so as to correct the other one running data to a predetermined value, that is, the case where such directions become reverse to each other. Therefore, an exactly corrected value, that is, a controlled variable cannot be determined.
In case where the control directions of one parameter by two running data are same with each other, this becomes the case of a control system of one output against two inputs (multiple inputs). Therefore, even though the parameter may be controlled by the value resulting from merely adding the controlled variables obtained every running data or the average value of the controlled variables obtained every the running data, both of two running data are not always attained within the range of objective values, and therefore, the controlled variables thus obtained cannot be always correct.
For example, in case of trying to simultaneously control a main pressure by both of the average value and the dispersion of arrival timing, this becomes similarly the case of a control system of one output (main output) against two inputs (average value and dispersion). Therefore, there are some cases where the control directions of outputs are opposite to each other depending on the combination of both input signals.
Namely, when the average value is rapid and the dispersion is large, the main pressure must be lessened since the average value is rapid. On the other hand, the main pressure must be increased since the dispersion is large. Thus, any correct controlled variables cannot be determined since the control directions of the outputs are opposite to each other.
As a result, there are no helps but largely depending on the professional perceptions and experiences of operators, and the control of weft inserting described above could not be automated.